1. Field of the Invention
The present invention relates to an improved controlled release system that can be incorporated into anhydrous cosmetic formulations such as powders, sticks, and sprays that provides moisture triggered release, fragrance or flavor transition, as well as, prolong release of fragrances, flavors, and other active ingredients onto the target site over an extended period of time.
2. Description of the Related Art
The cosmetic industry has searched many years for ways to enhance the performance of consumer and diversified products and make them more aesthetically pleasing for the consumers. Consumer acceptance of cosmetic products is determined not only by the performance achieved with these products but the aesthetics associated therewith. Fragrances and flavors are an important aspect of the successful cosmetic products and they are being utilized, in addition to imparting an aesthetically pleasing odor, or a taste, to convey to the consumer the product performance and effectiveness.
Consumers are becoming increasingly educated and expect a high level of sophistication in their cosmetic products and the cosmetic market has become extremely competitive. Many consumers would prefer for the fragrance, or the flavor present in these products, to be remained on the area of application for an extended period of time. Also, there is a need for a controlled release system that will provide a signal, such as a change in odor character, or flavor character, upon activation of the product or to signal that a new application is needed. There is also a need for controlled release systems that provide special performance features to differentiate the product from that of the competitor.
U.S. Pat. No. 3,971,852 discloses the use of spray-dried particles of starch derivatives, natural gums (e.g., gum arabic), and polyhydroxy compounds (i.e., mannitol, sorbitol) in cosmetic, personal care, and household products. The drawback of these types of materials is the relatively large amount of surface oil, sometimes up to 12%. As a result, the retention of volatile fragrance ingredient may be poor leading to premature leaking of the fragrance. These types of materials, also quickly release the fragrance, or other active ingredients that are encapsulated within their structure upon exposure to water, and would not have the ability to extend the release of fragrances, flavors, and other active ingredients over an extended period of time.
U.S. Pat. No. 5,945,095 discloses a composition, in particular a cosmetic, dermatological, hygiene or pharmaceutical composition, to care for and/or make up the skin, which composition may be in the form of a compact powder or a cast product, comprising a dispersion of polymer particles in a fatty substance. Furthermore, the invention relates to the use of this dispersion in such a composition.
A controlled release system for cosmetic and pharmaceutical products based on spray-dried multilamellar phospholipid liposomes is disclosed in U.S. Pat. Nos. 5,783,211 and 6,045,823. The liposomes encapsulate a biologically active agent is selected from the group consisting of anti-inflammatory, antiphlogistic, antibacterial, antiperspirant, astringent, and anti-fungal agents. The problems with using liposomes and structured vesicles as delivery devices are manifold. These types of systems are unstable, and can only be used for encapsulation of certain types of materials. The liposomes disclosed in U.S. Pat. Nos. 5,783,211 and 6,045,823 are released in response to moisture but are not able to sustain the release of the active agents over an extended period of time because liposomes are is not stable. The problems with using the liposomes and structured vesicles that are disclosed in disclosed in U.S. Pat. Nos. 5,783,211 and 6,045,823 as delivery systems, are that these types of systems are very dynamic, unstable in aqueous compositions, and can only be used for encapsulation of certain types of materials. Stability has become the major problem limiting the use of liposomes for controlled delivery, both in terms of shelf life and after administration.
The prior art of which applicant is aware does not set forth a controlled release system that comprises of solid hydrophobic nano-spheres encapsulated in a moisture sensitive micro-sphere that can be incorporated in anhydrous cosmetic formulations such as powders, sticks, and sprays (i.e., deodorant body powders, lip bahns, lip sticks, make-up sticks, and underarm deodorant or antiperspirant sticks, body sprays, foot spray, hygiene sprays, feminine napkin sprays, undergarment sprays, etc.) and can encapsulate one or more different fragrances, flavors, or combinations of fragrances, flavors, and various active ingredients.